Re: [PATCH] mtd: orion_nand: fix error code path in probe

Andrew Lunn
2014-10-14T21:36:05Z

On Tue, Oct 14, 2014 at 04:16:38PM +0200, Michael Opdenacker wrote:
> This replaces kzalloc() and ioremap() calls by
> the corresponding devm_ functions in the probe() routine,
> which automatically release the corresponding resources
> when probe() fails or when the device is removed.
>
> This simplifies the error management code and
> fixes a bug reported by "make coccicheck":
>
> if "board = devm_kzalloc()" fails, the probe()
> function jumps incorrectly to label "no_res" and
> therefore returns without running "iounmap()"
>
> Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
> ---
> drivers/mtd/nand/orion_nand.c | 28 +++++++++-------------------
> 1 file changed, 9 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mtd/nand/orion_nand.c b/drivers/mtd/nand/orion_nand.c
> index 471b4df3a5ac..a9c2bde16c25 100644
> --- a/drivers/mtd/nand/orion_nand.c
> +++ b/drivers/mtd/nand/orion_nand.c
> @@ -19,7 +19,7 @@
> #include <linux/mtd/partitions.h>
> #include <linux/clk.h>
> #include <linux/err.h>
> -#include <asm/io.h>
> +#include <linux/io.h>
> #include <asm/sizes.h>
> #include <linux/platform_data/mtd-orion_nand.h>
>
> @@ -85,32 +85,30 @@ static int __init orion_nand_probe(struct platform_device *pdev)
> int ret = 0;
> u32 val = 0;
>
> - nc = kzalloc(sizeof(struct nand_chip) + sizeof(struct mtd_info), GFP_KERNEL);
> + nc = devm_kzalloc(&pdev->dev,
> + sizeof(struct nand_chip) + sizeof(struct mtd_info),
> + GFP_KERNEL);
> if (!nc) {
> - ret = -ENOMEM;
> - goto no_res;
> + return -ENOMEM;
> }
> mtd = (struct mtd_info *)(nc + 1);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> if (!res) {
> - ret = -ENODEV;
> - goto no_res;
> + return -ENODEV;
> }
>
> - io_base = ioremap(res->start, resource_size(res));
> + io_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> if (!io_base) {
> dev_err(&pdev->dev, "ioremap failed\n");
> - ret = -EIO;
> - goto no_res;
> + return -EIO;
> }

Hi Michael

It is quite a common pattern to use:

res = platform_get_resource(dev, IORESOURCE_MEM, 0);
c->membase = devm_ioremap_resource(&dev->dev, res);
if (IS_ERR(c->membase))
return PTR_ERR(c->membase)

which is more compact.

>
> if (pdev->dev.of_node) {
> board = devm_kzalloc(&pdev->dev, sizeof(struct orion_nand_data),
> GFP_KERNEL);
> if (!board) {
> - ret = -ENOMEM;
> - goto no_res;
> + return -ENOMEM;
> }

Doesn't this now break the coding style? No need to have the {} since
it is a single statement.

Andrew